Can Quiet, Efficient 'Space Elevators' Really Work?
By Leonard David, Space.com's Space Insider Columnist | February 19, 2014 06:38am ET
Posted on 02/22/2014 8:13:46 PM PST by ckilmer
 |
 An electric-powered climber spacecraft rides up the space elevator.Credit: Frank Chase/Chase Design Studios |
Is it time to push the "up" button on the space elevator?
A space elevator consisting of an Earth-anchored tether that extends 62,000 miles (100,000 kilometers) into space could eventually provide routine, safe, inexpensive and quiet access to orbit, some researchers say.
A new assessment of the concept has been pulled together titled "Space Elevators: An Assessment of the Technological Feasibility and the Way Forward." The study was conducted by a diverse collection of experts from around the world under the auspices of the International Academy of Astronautics (IAA). [Quiz: Sci-Fi vs. Real Technology]
The study's final judgment is twofold: A space elevator appears possible, with the understanding that risks must be mitigated through technological progress…and a space elevator infrastructure could indeed be built via a major international effort.
The tether serving as a space elevator would be used to economically place payloads and eventually people into space using electric vehicles called climbers that drive up and down the tether at train-like speeds. The rotation of the Earth would keep the tether taut and capable of supporting the climbers.
Rooted in history
The notion of a beanstalk-like space elevator is rooted in history.
Many point to the ahead-of-its-time "thought experiment" published in 1895 by Russian space pioneer Konstantin Tsiolkovsky. He suggested creation of a free-standing tower reaching from the surface of Earth to the height of geostationary orbit (GEO; 22,236 miles, or 35,786 km).
Reach for the sky. Image depicts key elements of a space elevator, from top to bottom.Over the last century or so, writers, scientists, engineers and others have helped finesse the practicality of the space elevator. And the new study marks a major development in the evolution of the idea, says IAA president Gopalan Madhavan Nair. [10 Sci-Fi Predictions That Came True]
"No doubt all the space agencies of the world will welcome such a definitive study that investigates new ways of transportation with major changes associated with inexpensive routine access to GEO and beyond," Nair writes in the new study's preface.
"There is no doubt that the Academy, due to this study, will contribute to advancing international consensus and awareness on the need to search and develop new ways of transportation in conducting space exploration while preserving our universe in the same way we are now trying to preserve our planet Earth," Nair adds.
Elevator operator
While it's always tricky to predict the future study lead editor Peter Swan told Space.com that space elevators are more than just a science-fiction fantasy. "The results of our study are encouraging," he said.
Swan's view is fortified by the late science fact/fiction soothsayer, Arthur C. Clarke, who stated in 2003: "The space elevator will be built ten years after they stop laughing…and they have stopped laughing!"
Swan is chief engineer at SouthWest Analytic Network, Inc. in Paradise Valley, Ariz., and is focused on developing and teaching innovative approaches to "new space" development. He's also head elevator operator of the International Space Elevator Consortium (ISEC), which has organizational members in the United States, Europe and Japan and individual members from around the world.
ISEC's goal is nothing short of getting a lengthy space elevator built.
"The question is when, of course," Swan said. "But the point is that the technologies are progressing in a positive manner, such that we who work in it believe that there will be space elevators."
Climber ascends space elevator, heading spaceward from its aeroshell.Pacing technologies
Swan said the giggle factor regarding space elevators is "down significantly" given work carried out over the last decade by a global network of individuals and groups. "Still, there are many, many issues and I certainly would not want to say that it's not a challenging project."
The IAA appraisal delves into a number of issues, such as: Why build a space elevator? Can it be done? How would all the elements fit together to create a system of systems? And what are the technical feasibilities of each major space elevator element
?
Two technologies are pacing the development of the space elevator, Swan said.
Producing an ultra-strong space tether and other space elevator components, Swan said, has been advanced by the invention of carbon nanotubes (CNTs) that are 1,000 times better in strength-to-weight ratio than steel. The good news, he said, is that CNTs are being developed with billions of dollars by nanotechnology, electronics, optics, and materials specialists.
Similarly, lightweight solar cells "are coming along nicely," Swan said. "That's an industry that the space elevator people are watching, too. We're not going to drive it, but we can certainly watch it and appreciate the advances."
Money, motivation and desire
Regarding who would erect a space elevator, Swan said the study dives into details. A primarily commercial effort with some government support is possible, as is a public-private enterprise, or an entirely governmental project.
"All three are viable. Any one of them could work. It's a matter of money, motivation and the desire to do it," Swan said, though the study centers on commercial development of the space elevator. "It's conceivable all three could be going on at the same time."
The study team was encouraged by the future, though Swan and others acknowledge there are many questions left to be studied. Indeed, another evaluation of the space elevator idea 10 years hence would be worthwhile, Swan said.
Erasing the rocket equation
Space elevator makes use of an ocean platform to connect Earth with space.Are there any technical, political or policy "showstoppers" that could prevent the space elevator from becoming a reality?
"You're asking the wrong guy," Swan responded. "I am an optimist. I have always had the attitude that good people, motivated by good rationale working hard will make it work. My guess is that space elevators are going to work, whether it's by 2035, 2060 or even 2100."
Swan said the rationale is moving beyond the "rocket equation," which involves tossing away 94 percent of a rocket's mass sitting on the launch pad.
"And it still costs a lot of stinking money to get up there," he said.
The space elevator opens everything up, Swan said. It's a soft ride, a week to GEO. There are no restrictions on the size or shape of payloads.
"People will laugh and ask why did we ever do space rockets…it's a dumb idea," Swan said. "Space elevators are the answer if we can make them work. Why would you do anything else?"
A copy of "Space Elevators: An Assessment of the Technological Feasibility and the Way Forward" is available through Virginia Edition Publishing Company at: www.virginiaedition.com/sciencedeck
Fine and good until it stops and people are stuck on the darn thing!
62,000 miles at “at train-like speeds?”
If the train-like speed is based on Amtrak they better pack a lunch.
Seriously, even at the speed of a bullet train or ICE the trip up will take up to 13 days.
Ok, so the line gets cut what happens? Does it fly into space hitting satellites, like in the picture Gravity? There is so much crap up there, what havoc would it reek?
You forgot to mention Union Labor.
Seems like something that massive would be affected by lunar cycles.
Imagine the logistics of the “Environmental Impact Study.”
How do we keep space junk from hitting the cable?
Let passengers lean out the windows and fire bazookas at it. Charge them $5 per shot. The kids will love it.
Future of Space Elevator Looks Shaky
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http://www.freerepublic.com/focus/news/2146158/posts
The space elevator: going down?
Nature | 05/22/06 | Jason Palmer
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http://www.freerepublic.com/focus/chat/1636686/posts
Transportation - New Ways to New Places
Jim Cline’s web pages | May 2000 | James Edward David Cline
Posted on 10/30/2006 12:14:07 AM by SunkenCiv
http://www.freerepublic.com/focus/chat/1728306/posts
I said "your place" not "outer space"...
I’m not so sure that they’ll go the entire distance on the elevator. The line may have be anchored out at 62000 miles but they may only go up part of the distance. Low earth orbit after all is only a couple hundred miles up.
That would be a stairway to heaven.
Yup. In the Bible, angels flew and people didn’t. Glad we didn’t invent that devil machine the airplane...
Um, nevermind.
It’s 62,000 miles long to keep it taunt and the force equal at both ends. 26 days if you go all the way to the end.
However, payloads could detach at around 150 miles up and would be weightless. We could first haul up parts to make a fleet of reentry-less shuttles that can grab payloads at 100-150 miles up and bring them further (and a lot faster) to orbital space stations, etc. Fuel for the shuttles can go up the tether, too. And since the shuttles wouldn’t need to waste 98% of their fuel getting off the Earth, they could go a long ways hauling stuff around near-Earth to high-Earth orbit.
Bigger shuttles could be built up there in space for longer hauls, say to comets and asteroids for additional raw materials. Comets are big snow balls, full of ice that can be melted and using continuous orbital solar power broken down into hydrogen (fuel) and oxygen (life support).
I say it IS the future.
That's why a space elevator isn't going to save any money over a rocket. You still have to add the same amount of energy to an object to get it to stay in orbit. A space elevator doesn't provide any cost advantage.
I was just speaking of the tangibility of Jacob’s ladder to humans, is all.
As for our elevator here, it reminds me of da Vinci’s helicopter.
having dealth with cable stretch and tensile strengths when logging oil wells to a mile and more it always amazes me that no one discusses cable stretch during these space elevator conversations.
Environmentalists will find an endangered three spotted winged toad and will shut the project down.
So that means that the real problem will be geopolitical.
The only countries that could host it are:
-PJ
The size, the forces to manage and thus the materials of a space elevator depend on the size of the base body. Smaller bodies mean lower geostationary orbits thus shorter cables, and less tensile strength required so less exotic materials. Building one on earth with what most would consider 'conventional' materials isn't possible and, at least, pushes the theoretical limits of what might be done with unconventional ones. It would be significantly easier on our moon and straightforward on Deimos (a mere 13 miles long if my math is correct.) Well, other than the problems with getting to the construction site. Which seem relatively small compared to conceiving an earthly space elevator.
Other than as a proof of concept demonstration, I can't think of short term economic benefits of a Deimos elevator. But I suspect Obama has already spent more than it would cost... with less benefits. It might even be possible to install it remotely via robots. Its novelty would certainly command public interest and might prove to be worth its cost in PR.
A lunar elevator would be more difficult, but would have obvious utility to anyone trying to expand into space. It would allow complex earth products easier access to an expanding lunar base and would allow cheap (in gravity boost costs) lunar raw materials be used in place of expensive earth source ones for both earth and lunar orbital construction. Other than weather and extreme materials, it would require dealing with most of the real issues an earthly elevator would require. Over time its mere presence would remove most of the unreal issues as public concern.
Alas, before we can consider any of these we'll probably have to defeat the philosophical adversaries holding us back. Socialism, environmentalism, etc. won't leave us the needed capital to invest is such big projects.
Nicola M. Pugno
Department of Structural Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Italy; nicola.pugno@polito.it
Abstract In this paper different deterministic and statistical models, based on new quantized theories proposed by the author, are presented to estimate the strength of a real, thus defective, space elevator cable. The cable, of ~100 megameters in length, is composed by carbon nanotubes, ~100 nanometers long: thus, its design involves from the nano- to the mega-mechanics. The predicted strengths are extensively compared with the experiments and the atomistic simulations on carbon nanotubes available in the literature. All these approaches unequivocally suggest that the megacable strength will be reduced by a factor at least of ~70% with respect to the theoretical nanotube strength, today (erroneously) assumed in the cable design. The reason is the unavoidable presence of defects in a so huge cable. Preliminary in silicon tensile experiments confirm the same finding. The deduced strength reduction is sufficient to pose in doubt the effective realization of the space elevator, that if built as today designed will surely break (according to the author’s opinion). The mechanics of the cable is also revised and possibly damage sources discussed.
Kind of like the Columbia canal. We found a reasonably good way around that. At least until Jimmy Carter came along. Like present day Somalia, the then current value of the land, under the status quo, was worthless. It was a pestilent hellhole. Only its location had value.
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